[llvm][lit] Add option to run only the failed tests (#158043)

This patch adds a new `--filter-failed` option to `llvm-lit`, which when
set, will only run the tests that have previously failed.

Author: Michael137

llvm/docs/CommandGuide/lit.rst

@@ -314,6 +314,11 @@ The timing data is stored in the `test_exec_root` in a file named
   place of this option, which is especially useful in environments where the
   call to ``lit`` is issued indirectly.
 
+.. option:: --filter-failed
+
+  Run only those tests that previously failed. Tests that have been newly added
+  but not yet run are not included.
+
 .. option:: --xfail LIST
 
   Treat those tests whose name is in the semicolon separated list ``LIST`` as

llvm/utils/lit/lit/TestTimes.py

@@ -22,7 +22,7 @@ def record_test_times(tests, lit_config):
             continue
         if not t.suite.exec_root in times_by_suite:
             times_by_suite[t.suite.exec_root] = read_test_times(t.suite)
-        time = -t.result.elapsed if t.isFailure() else t.result.elapsed
+        time = min(-t.result.elapsed, -1.0e-6) if t.isFailure() else t.result.elapsed
         # The "path" here is only used as a key into a dictionary. It is never
         # used as an actual path to a filesystem API, therefore we use '/' as
         # the canonical separator so that Unix and Windows machines can share

llvm/utils/lit/lit/cl_arguments.py

@@ -423,6 +423,12 @@ def parse_args():
         help="Filter out tests with paths matching the given regular expression",
         default=os.environ.get("LIT_FILTER_OUT", "^$"),
     )
+    selection_group.add_argument(
+        "--filter-failed",
+        dest="filterFailed",
+        help="Only run tests which failed in the previous run",
+        action="store_true",
+    )
     selection_group.add_argument(
         "--xfail",
         metavar="LIST",

llvm/utils/lit/lit/main.py

@@ -90,6 +90,9 @@ def main(builtin_params={}):
         and not opts.filter_out.search(t.getFullName())
     ]
 
+    if opts.filterFailed:
+        selected_tests = [t for t in selected_tests if t.previous_failure]
+
     if not selected_tests:
         sys.stderr.write(
             "error: filter did not match any tests "

llvm/utils/lit/tests/Inputs/filter-failed/fail.txt

@@ -0,0 +1 @@
+RUN: false

llvm/utils/lit/tests/Inputs/filter-failed/lit.cfg

@@ -0,0 +1,7 @@
+import lit.formats
+
+config.name = "filter-failed"
+config.suffixes = [".txt"]
+config.test_format = lit.formats.ShTest()
+config.test_source_root = None
+config.test_exec_root = None

llvm/utils/lit/tests/Inputs/filter-failed/pass.txt

@@ -0,0 +1 @@
+RUN: true

llvm/utils/lit/tests/Inputs/filter-failed/unresolved.txt

@@ -0,0 +1,2 @@
+RUN: false
+XFAIL: *

llvm/utils/lit/tests/Inputs/filter-failed/xfail.txt

@@ -0,0 +1,2 @@
+RUN: true
+XFAIL: *